Blockchain technology has become a foundational component for constructing decentralized, secure, and immutable distributed systems. The consensus mechanism ensures that all nodes in a blockchain network reach agreement on a single version of truth, thereby maintaining data consistency across the distributed ledger. The earliest blockchain application, Bitcoin, adopts Proof of Work (PoW), which provides high security at the cost of substantial computational power and energy consumption. Ethereum employs Proof of Stake (PoS) to reduce energy consumption, though it introduces new challenges in the fairness of node selection. Practical Byzantine Fault Tolerance (PBFT) has gained significant attention for its ability to achieve more efficient consensus by reducing computational and energy demands. However, traditional PBFT still requires extensive message exchanges and voting among nodes, leading to significant communication overhead in large-scale networks. To address these limitations and further enhance the performance of PBFT, we propose the Comprehensive Trust-based PBFT (CTPBFT) algorithm. CT-PBFT reduces communication overhead by excluding nodes with low trust scores from the consensus process, thereby optimizing overall efficiency. We conducted a thorough analysis and simulation of CT-PBFT, and the results demonstrate that CT-PBFT outperforms traditional PBFT in terms of consensus latency and throughput. Moreover, CT-PBFT is more effective than other trust-based PBFT variants in swiftly eliminating Byzantine nodes, providing a robust and efficient solution for secure communication in distributed systems.
Over the last few decades, a large body of research was carried out covering Byzantine Fault Tolerance (BFT) systems. This research has brought forward new techniques, including but not limited, for ordering operations (Abraham et al., 2018; Buchman, 2016; Guo et al., 2020; Bessani et al., 2014; Duan et al., 2018) and state transfer (Bessani et al., 2013; Distler, 2021 , Eischer et al., 2019 ), on networks that suffer from byzantine faults. More recently, the ongoing research on distributed ledgers re-ignited the interest on BFT, due to its high throughput when compared to other alternatives of byzantine consensus ( Vukolić, 2016 ). In this paper we present three contributions covering several aspects, including modular and extensible framework design and implementation, system optimization through development of better networking alternatives, a greater use of parallelism, several ordering protocol improvements and extensive comparative assessment of previous state-of-the-art approaches. First, we introduce Atlas, an open-source modular BFT framework that aims to support the research and development of highly efficient BFT protocols, by decoupling traditionally entangled sub-protocols, e.g., consensus primitive from the execution (Bessani et al., 2014), and deferment of log management to replicated services from state transfer. Atlas allows to further provide modules that can be re-used across different BFT approaches, such as deterministic and probabilistic/randomized models. Second, we present FeBFT, a new BFT implementation developed upon Atlas that combines pre-existing proven ideas from PBFTs, namely its 3-phase consensus and view-change protocol. This base approach is then extended with novel optimizations of the protocol, namely, multi-leader proposals (Stathakopoulou et al., 2019), multi-instance consensus execution (Stathakopoulou et al., 2022; Behl et al., 2015), and configurable batching solution that allow us to reduce the latency while improving throughput at the same time. Third, we offer a comprehensive evaluation amongst our work and other state-of-the-art BFT-SMR implementations, namely, Atlas ( Anon, 2024a ) with FeBFT (Official febft repository 2024), BFT-SMaRt (Bessani et al., 2014) and Themis (Rüsch et al., 2019). With these contributions, we aim to lay the ground work to: (i) improve reusability and hence productivity in BFT(-SMR) development; (ii) increase system safety, performance, scalability and reduce recovery time with the optimizations proposed; (iii) draw insights on the bottlenecks preventing order-of-magnitude improvements in BFT processing from a system’s perspective; and lastly, (iv) improve reproducibility between different BFT (sub-)protocols by allowing for true apples-to-apples comparisons. • Atlas, an open-source, modular BFT framework designed to support the efficient development of BFT protocols by separating traditionally intertwined sub-protocols and allowing for reusable modules across different BFT approaches. • FeBFT, introduces a novel BFT implementation leveraging the Atlas framework, which boosts protocol efficiency via multi-leader proposals and multi-instance consensus execution. It incorporates a batching solution designed to scale with network throughput, prioritizing this over network latency while maintaining the configurability to be tuned for low latency if needed. • Focusing on the essential need for reproducibility in scientific evaluation, Atlas provides a critical framework for accurate comparisons between different protocols. By offering a modular and reusable architecture, it significantly reduces the workload for system researchers in developing and testing implementations. This approach ensures a true apple-to-apple comparison, enabling a more precise and reliable assessment of protocol performance and efficacy. • And lastly, a comprehensive evaluation comparison with two well-known BFT-SMR (deterministic) implementations, namely, BTF-SMaRt and Themis, against FeBFT, our PBFT implementation that uses Atlas.
There have been many attacks threatening the security of LMD-GHOST, the consensus protocol adopted in Ethereum 2.0. Therefore, a consensus protocol which is provably secure is needed. The existing work "Goldfish" is provably secure but requires 3Δ rounds per slot, with Δ being the maximum network delay. In this study, we propose a provably secure protocol with a structure of 2Δ rounds per slot by parallelizing the block proposal phase and the voting phase in Goldfish. By reducing the number of rounds per slot, transaction processing speed increases, leading to enhancing scalability.
Conner Fulford, Sai Medury, Amani Altarawneh, Anthony Skjellum
Distributed systems and blockchain consensus protocols rely on a clock synchronization algorithm to resolve any conflicts related to the state of data or resources. Faulty and adversarial peers make it challenging to achieve clock synchronization in a peer-to-peer distributed system. Clock-synchronization protocols such as the Network Time Protocol (NTP) and the Precision Time Protocol (PTP) are effective but only in a partially or fully trusted network. They fail to synchronize clocks in the presence of misbehaving peers who try to rewind or fast-forward time or introduce deadlocks purposely.This paper introduces BFT-Metronome, a Byzantine fault-tolerant clock synchronization algorithm for peer-to-peer distributed systems. The novel BFT-Metronome algorithm combines a sensor-fusion algorithm with a statistical outlier detection algorithm to enable participating peers to determine the most likely skew based on broadcast timestamps. The algorithm is designed to withstand up to $\frac{N}{3} - 1$ misbehaving participants in a network of N total participants, and the independently calculated offset is observed to be within 10 ms of precision vs. 40-100 ms in peer-to-peer distributed systems.The BFT-Metronome clock synchronization algorithm can also be applied to blockchain consensus protocols (such as Proof-of-Stake) that rely on weakly synchronized clocks. This is shown by integrating BFT-Metronome with the Lightweight Mining Algorithm to achieve consensus-round synchronization and timeouts. Then, generalization to other protocols is argued qualitatively. It can also be applied to large distributed systems to secure against insider threats during clock synchronization.
Maha Alaslani, Sonali Suri, Basem Shihada, Faisal Nawab
Blockchain technology is a distributed ledger system designed to securely process and store data. Although it offers several advantages when the number of participants increased, bolckchain will suffer from significant scalability challenges, such as the case of Internet of Things (IoT) networks. To address the specific needs of IoT, it is necessary to redesign consensus mechanisms and block formation processes. In this paper, we introduce Synopsis, an innovative hierarchical blockchain framework. Synopsis introduces a wireless-optimized Byzantine chain replication protocol and a novel probabilistic data structure. Both are designed to enhance locality and hierarchy, thereby improving system reliability and performance. We implemented Synopsis and evaluated its performance through extensive simulations and real-world testbed experiments. Our findings show that Synopsis effectively reduces the memory usage from Megabytes to just a few Kilobytes, achieving a 1000 time improvement. Synopsis also significantly decreases message complexity by 85% and commitment delay by 99.4%.
In database applications involving sensitive data, the dual imperatives of data confidentiality and provable (verifiable) query processing are important. This paper introduces PoneglyphDB, a database system that leverages non-interactive zero-knowledge proofs (ZKP) to support both confidentiality and provability. Unlike traditional databases, PoneglyphDB enhances confidentiality by ensuring that raw data remains exclusively with the host, while also enabling verifying the correctness of query responses by providing proofs to clients. The main innovation in this paper is proposing efficient ZKP designs (called circuits) for basic operations in SQL query processing. These basic operation circuits are then combined to form ZKP circuits for larger, more complex queries. PoneglyphDB's circuits are carefully designed to be efficient by utilizing advances in cryptography such as PLONKish-based circuits, recursive proof composition techniques, and designing with low-order polynomial constraints. We demonstrate the performance of PoneglyphDB with the standard TPC-H benchmark. Our experimental results show that PoneglyphDB can efficiently achieve both confidentiality and provability, outperforming existing state-of-the-art ZKP methods.
Chon Kit Lao, Sophie Zhou, Luyao Zhang, Fan Zhang · 5 authors
Blockchain systems such as Bitcoin and Ethereum have limitations in efficiency, resulting in an inability to immediately confirm all transactions, leading to extended periods of transactions residing in the mempool. We refer to these transactions as “long latency trans- actions” and this paper explores the issue of resource utilization in- efficiencies issues from these transactions. Utilizing the Geth client, the study quantifies the impact of these transactions on Ethereum’s resource consumption, which encompassing three crucial metrics: computational power, memory storage, and network bandwidth. Furthermore, this study also identifies three primary factors con- tributing to long latency transactions: low gas prices, long block processing times, and future-index transactions. Through empirical analysis, this study offers insights into the transaction-handling mechanisms in Ethereum. The implications of our findings aim to contribute to the enhancement of resource efficiency within the Ethereum blockchain ecosystem.
Ravi Kanth Kotha, Susmita Mandal, Tene Ramakrishnudu
Implementation of cross-enterprise business processes is complex. The globalization of businesses has resulted in a greater demand for business platforms that provide information security and privacy. In these processes, technological advancements are extensively leveraging automation and simplification. However, most enterprise systems are still centralized and work in silos. The advent of Distributed Ledger Technologies (DLT) and Smart Contracts is addressing some security and privacy challenges. However, these systems do not provide a perfect balance between end-to-end and cross-enterprise visibility and security. A further challenge is that the consensus/agreement provided by these systems cannot accommodate wider application requirements. The business platforms currently provide agreement at the level of individual messages without considering the context of the business workflow. This paper defines the Design-Centric Consensus (DCC) and information flow security inspired by the literature on information flow models and security protocols. It also identifies the need for multiple levels of consensus based on the application requirements. An architectural framework is also proposed that provides application-specific consensus while maintaining DCC and visibility
Distributed systems and fault tolerance
Systems Engineering Methodologies and Applications
Due to the susceptibility to nothing-at-stake and long-range attacks, the Proof-of-Stake consensus faces challenges in securely and efficiently confirming blocks. We propose a new Proof-of-Stake consensus, Voted Weightest Sub-Tree(VWeiST) consensus. It assigns weights to each block through voting, and nodes confirm blocks by calculating the probability that each block's weight can be exceeded by other competitors. We employ a multi-round voting approach, where a small number of nodes are randomly selected as the committee nodes to vote in each round. This approach results in particularly low communication overhead per block, allowing for scalability to a large number of nodes. Compared to other consensus, our mechanism requires fewer rounds of voting to confirm a block, offering advantages in throughput and transaction latency. In the experiments, VWeiST achieves latency and round reductions down to 40% and 29% of the comparison method's levels at most. Furthermore, we theoretically prove that the consensus ensures liveness and probabilistic safety.
The consensus protocol is a crucial element of blockchain technology that guarantees all participants agree on the same data values and follow the same direction, even in the presence of defective components. This research project has identified a problem that affects both users of blockchain technologies and investors in cryptocurrencies. The question of whether current blockchain platforms are truly decentralized has been raised by the blockchain community over the years. The most popular blockchains use Proof of Work (PoW), Proof of Stake (PoS), or a combination of both, but both systems have limitations in terms of decentralization. Several alternative consensus protocols have emerged recently, but none have achieved total decentralization or welcomed any level user to be the next miner or forger.Therefore, true decentralization of a blockchain system is more challenging as most of the popular consensus protocols were invented to accommodate decentralization but eventually, driven by the centralization of power. This research study proposes a truly decentralized consensus protocol that is capable to avoid the centralization of power even in the future regardless of the number of network participants. The protocol also makes sure it avoids the use of specialized hardware resources, decreases the level of energy consumption, and encourages network activities. Additionally, the new consensus protocol offers a more democratic and fair approach to blockchain consensus.Furthermore, the implemented solution underwent comprehensive testing to ascertain its level of decentralization. Considering the lack of a suitable metric for evaluating the practical extent of decentralization achieved by a blockchain system, this study adopted a set of requirements delineated in a prior investigation. Based on this assessment, it was determined that the solution has successfully attained genuine decentralization. Moreover, the test results demonstrate that the solution has achieved enhancement in terms of security and performance, thereby ensuring its effectiveness in circumventing the need for specialized hardware and reducing energy consumption.
Approche Théorie des jeux pour l'Étude de la Robustesse des Blockchains Game-theoretical approach for the study of Blockchain's Robustness Les blockchains ont suscité un intérêt mondial ces dernières années, prenant de plus en plus d'importance à mesure qu'elles influencent les technologies et la finance. Cette thèse explore la robustesse des protocoles blockchain, en se concentrant spécifiquement sur Ethereum Proof-of-Stake (PoS). Nous définissons la robustesse en termes de deux propriétés essentielles : la sécurité, qui garantit que la blockchain n'aura pas de blocs conflictuels permanents, et la vivacité, qui assure l'ajout continu de nouveaux blocs fiables.Notre recherche aborde l'écart entre les approches traditionnelles des systèmes distribués, qui classifient les agents comme étant soit honnêtes, soit byzantins (i.e., malveillants ou défaillants), et les modèles de théorie des jeux qui considèrent les agents rationnels motivés par des incitations. Nous explorons comment les incitations impactent la robustesse en utilisant les deux approches.La thèse est composé de trois analyses distinctes. Nous commençons par formaliser le protocole Ethereum PoS, définissant ses propriétés et examinant les vulnérabilités potentielles du point de vue des systèmes distribués. Nous identifions certaines attaques qui peuvent compromettre la robustesse du système. Ensuite, nous analysons le mécanisme de fuite d'inactivité, une caractéristique clé d'Ethereum PoS, en soulignant son rôle dans le maintien de la vivacité du système lors de perturbations du réseau, mais au détriment de la sécurité. Enfin, nous utilisons des modèles de théorie des jeux pour étudier les stratégies des validateurs rationnels au sein d'Ethereum PoS, en identifiant les conditions dans lesquelles ces agents pourraient s'écarter du protocole prescrit pour maximiser leurs récompenses.Nos résultats contribuent à une meilleure compréhension de l'importance des mécanismes d'incitation pour la robustesse des blockchains et donnent des pistes pour concevoir des protocoles blockchain plus résilients.
Increasingly popular decentralized applications (dApps) with complex application logic incur significant overhead for executing smart contract transactions, which greatly limits public blockchain performance. Pre-executing transactions off the critical path can mitigate substantial I/O and computation costs during execution. However, pre-execution does not yield any state transitions, rendering the system state inconsistent with actual execution. This inconsistency can lead to deviations in pre-execution paths when processing smart contracts with multiple state-related branches, thus diminishing pre-execution effectiveness. In this paper, we develop Seer, a novel public blockchain execution engine that incorporates fine-grained branch prediction to fully exploit pre-execution effectiveness. Seer predicts state-related branches using a two-level prediction approach, reducing inconsistent execution paths more efficiently than executing all possible branches. To enable effective reuse of pre-execution results, Seer employs checkpoint-based fast-path execution, enhancing transaction execution for both successful and unsuccessful predictions. Evaluations with realistic blockchain workloads demonstrate that Seer delivers an average of 27.7× transaction-level speedup and an overall 20.6× speedup in the execution phase over vanilla Ethereum, outperforming existing blockchain execution acceleration solutions.
Ningyuan Chen, Chiew Foong Kwong, David Chieng, Pushpendu Kar
The advent of Cellular Vehicle-to-Everything (C-V2X) technology has revolutionized intelligent transportation systems (ITS), but poses challenges for secure and efficient data sharing due to its dynamic nature. Traditional centralised systems are inadequate, prompting the need for decentralised solutions like blockchain. However, applying blockchain technologies in C-V2X always faces scalability issues. This paper proposes a scalable C-V2X blockchain network integrating dynamic attribute-based sharding and zero-knowledge proofs (ZKPs). Our system ensures scalability in the C-V2X environment through sharding while utilising ZKPs to enhance cross-shard validation efficiency, reducing its complexity to O(1). Additionally, our approach reduces bandwidth consumption by 90.8% compared to Merkle tree-based solutions.
Francesco D’Amato, Roberto Saltini, Thuy-An Tran, Luca Zanolini
Gasper, the consensus protocol currently employed by Ethereum, typically requires 64 to 95 slots -- the units of time during which a new chain extending the previous one by one block is proposed and voted -- to finalize. This means that under ideal conditions -- where the network is synchronous, and all chain proposers, along with more than two-thirds of the validators, behave as dictated by the protocol -- proposers construct blocks on a non-finalized chain that extends at least 64 blocks. This exposes a significant portion of the blockchain to potential reorganizations during changes in network conditions, such as periods of asynchrony. Specifically, this finalization delay heightens the network's exposure to Maximum Extractable Value (MEV) exploits, which could undermine the network's integrity. Furthermore, the extended finalization period forces users to balance the trade-off between economic security and transaction speed. To address these issues and speed up finality, we introduce a partially synchronous finality gadget, which we combine with two dynamically available consensus protocols -- synchronous protocols that ensure safety and liveness even with fluctuating validator participation levels. This integration results in secure ebb-and-flow protocols [SP 2021], achieving finality within three slots after a proposal and realizing 3-slot finality.
This report presents the results of a PhD thesis focused on the creation of a decentralised and autonomous identity structure. This structure allows users not only to store their identities, but also to generate them autonomously, without the need for a trusted third party or an external validation structure. To implement this concept, the 3BI-ECC framework, a network system based on blockchain and the cryptographic advantages of elliptic curves, has been designed to establish a decentralised consortium network of self-generated identities. In addition, a new blockchain structure called NestedChain was created, which allows two types of information to be stored simultaneously: the identity of users through smart contracts and the certification elements of the network. The Nested-C protocol has also been developed, a new consensus protocol that improves the efficiency and security of storing transactions on the blockchain. In addition, solutions are proposed to preserve the integrity of the information in each smart contract and in its transactions with the theoretical scheme. This research aims to create decentralised environments where each user controls their information on the network, protecting both their identity and the privacy of their data, thus promoting user autonomy in the digital environment.
Blockchain technology has revolutionized decentralized systems by enabling secure, transparent, and tamper-resistant data management. Central to blockchain functionality is the consensus mechanism, which ensures agreement among distributed nodes. This paper presents a comprehensive review of cryptographic solutions underpinning various blockchain consensus protocols. We analyze the role of cryptographic primitives such as hash functions, digital signatures, zero-knowledge proofs, and threshold cryptography in enhancing security and efficiency of consensus algorithms like Proof of Work (PoW), Proof of Stake (PoS), and Practical Byzantine Fault Tolerance (PBFT). The review highlights strengths, limitations, and emerging trends in cryptographic techniques addressing scalability, privacy, and resistance to adversarial attacks. Finally, we discuss future research directions toward integrating advanced cryptography with blockchain consensus to improve trustworthiness and performance.
In the last ten years-blockchain technology has changed a lot. It started as basic records shared across many computers and has become advanced networks that can do many things. Therefore, this study looks at how well blockchain systems can handle complex math problems for security. We focus on creating a system that puts timestamps on events. This method combines Schnorr signatures and Pedersen commitments. We use the Ethereum network to store and check data. The system uses a smart contract to manage data and connect servers and clients. Servers put timestamps on events and clients send data to be timestamped and checked. This setup makes sure they are clear and reliable. However, the study tests how well the system works by looking at cost-how much memory it uses and how fast it runs. The study also talks about using Ethereum. Ethereum lets everyone see timestamps and what happen-which is good for trust. But it can't keep secrets-so it's not good for private data. This study shows that blockchain is useful for more than just money. It can make sure events are real and safe. By mixing math ideas in blockchain-the study shows how to make data safer and more reliable in many places.
A. Jabbari, Gowri Ramachandran, Sidra Malik, Raja Jurdak
In the current digital landscape, supply chains have transformed into complex networks driven by the Internet of Things (IoT), necessitating enhanced data sharing and processing capabilities to ensure traceability and transparency. Leveraging Blockchain technology in IoT applications advances reliability and transparency in near-real-time insight extraction processes. However, it raises significant concerns regarding data privacy. Existing privacy-preserving approaches often rely on Smart Contracts for automation and Zero Knowledge Proofs (ZKP) for privacy. However, apart from being inflexible in adopting system changes while effectively protecting data confidentiality, these approaches introduce significant computational expenses and overheads that make them impractical for dynamic supply chain environments. To address these challenges, we propose ZK-DPPS, a framework that ensures zero-knowledge communications without the need for traditional ZKPs. In ZK-DPPS, privacy is preserved through a combination of Fully Homomorphic Encryption (FHE) for computations and Secure Multi-Party Computations (SMPC) for key reconstruction. To ensure that the raw data remains private throughout the entire process, we use FHE to execute computations directly on encrypted data. The "zero-knowledge" aspect of ZK-DPPS refers to the system's ability to process and share data insights without exposing sensitive information, thus offering a practical and efficient alternative to ZKP-based methods. We demonstrate the efficacy of ZK-DPPS through a simulated supply chain scenario, showcasing its ability to tackle the dual challenges of privacy preservation and computational trust in decentralised environments.
The adoption of smart contracts in decentralized blockchain-based applications enables reliable and certified audits. These audits allow the extraction of valuable information from blockchains, which can be used to reconstruct the execution of the application and facilitate advanced analyses. One of the most commonly used techniques in this context is process mining, which leverages event logs to trace and accurately represent the process execution of applications. However, extracting execution data from blockchains poses significant challenges, and the current methodologies developed have some limitations. Most approaches are tailored to specific use cases, requiring that analysis techniques are defined during the smart contract’s development. Other techniques are applied a posteriori, relying on blockchain events that often lack a standardized format. This absence of standardization requires complex processing steps to correlate logs with the executed actions and such approaches are not universally applicable to all smart contracts on the blockchain , further limiting their scope. Lastly, none of the existing techniques can extract information from event logs embedded in internal transactions of smart contracts. To address these limitations, we propose EveLog an application-agnostic methodology that can be applied to any EVM-compatible application without predefined constraints. Its primary goal is to extract information from smart contracts, capturing both public and internal transactions, and organizing the results into a structured XES event log. The EveLog methodology consists of five key steps: (i) extraction of data from smart contract transactions, (ii) decoding raw data, (iii) selection of sorting criteria, (iv) construction of traces, and (v) generation of the XES event log. EveLog has been implemented in a client–server application and tested on existing solutions, specifically the CryptoKitties application, a blockchain-based game on the Ethereum blockchain. The study was conducted using 12,996 blocks, including over 8000 real transactions from the Ethereum mainnet.
Oct 17, 2024·Companion Proceedings of the 2024 ACM SIGPLAN International Conference on Systems, Programming, Languages, and Applications: Software for Humanity
Zero-knowledge virtual machines (zkVMs) enable verifiable computation on via succinct Zero-knowledge proofs (ZKPs). However, current zkVMs, still in development, show many bugs. This paper introduces a parameterized framework for the formal verification of zkVMs in Coq. We prove the soundness and completeness of the constraint generation algorithm from machine instructions to semantics-level constraints. Existing works target specific zkVMs, and require repeated proof work in this phase, whereas our proofs are parameterized and can be reused in development and by all zkVMs. We also demonstrate the generality of our framework by instantiation on two examples: Cairo VM and a simplified zkEVM.